三種殺菌劑對除草劑達有龍在茶園土壤中之降解及土壤菌相的影響
Other Title
Effects of Three Fungicides on the Degradation of Diuron and Bacterial Community in the Tea Field Soil
Journal
臺灣農藥科學
Journal Issue
15
Start Page
37
End Page
54
ISSN
2518-9751
Date Issued
2023
Author(s)
Abstract
現代農業為減少人力常混合或連續施用農藥，使得田間同時殘留不同種類的農藥，其中殺菌劑的施用可能會衝擊土壤微生物族群，進而影響微生物除草劑的降解及流布。本研究為探討茶園土壤中施用三種殺菌劑，免賴得（benomyl）、得克利（tebuconazole）及三泰芬（triadimefon）對除草劑達有龍（diuron）在土壤中降解及對土壤菌相之影響，因此以不同殺菌劑與除草劑達有龍混合施用於土壤中進行孵育試驗。結果顯示達有龍在滅菌土壤中的降解速率比未滅菌土壤慢，顯示達有龍是以微生物性降解為主，此為文獻中已經證實的藥劑特性，在本研究中可作為可信度的對照處理。以免賴得及達有龍10倍推薦施用量下之處理使達有龍的持久性略微增加（達有龍DT_(50)自125.07天增加為141.59天）。50倍推薦施用量下，免賴得加達有龍及三泰芬加達有龍處理使達有龍在土壤中之持久性顯著的增加（達有龍DT_(50)自166.65天增加為231.48天及238.46天）。10倍推薦施用量處理偵測到達有龍之代謝產物N'-[3,4-di-chlorophenyl]-N,N-methylurea（DCPMU），50倍推薦施用量處理中偵測到DCPMU及N'-3,4-dichloro-phenylure（DCPU），而代謝產物之濃度隨孵育時間逐漸上升，顯示達有龍之代謝產物有累積的可能性。50倍推薦施用量下免賴得施加於土壤中明顯的抑制DCPMU的生成，進而造成達有龍降解速率趨緩。菌相及聚類分析結果顯示在10倍推薦施用量下，單獨施用達有龍、得克利加達有龍及三泰芬加達有龍處理可以促進土壤中細菌族群的豐富度。免賴得加達有龍相較其他三種處理，對土壤菌相的衝擊較大。50倍推薦施用量下，於試驗末期可以看出免賴得加達有龍及三泰芬加達有龍處理對菌相的衝擊是比較大的，進而推論達有龍降解速率的趨緩為殺菌劑影響菌相族群結構所造成。達有龍在土壤中與殺菌劑共同存在所產生的相互作用，可能會導致達有龍在土壤中的持久性增長。因此在施用達有龍的茶園土壤中，應審慎評估達有龍與殺菌劑間的效應，而避免達有龍於環境中的殘留。
To reduce costs associated with pesticide application, mixed or sequential pesticides application strategies are often employed in agricultural fields. Under these strategies insecticides, herbicides, and fungicides are applied simultaneously or sequentially. Tea is one of the most important economic agricultural products in Taiwan. Many pesticides are used to control weeds, diseases, and insects in tea fields, thereby ensuring high tea quality and good yield. In this study, we investigated the effects of various mixed pesticide application treatments. Specifically, three fungicides, benomyl (B), tebuconazole (Te) and triadimefon (Tr), were respectively combined with a herbicide, diuron (D), and the persistence of the various pesticide combinations in soil was investigated. We also investigated the effects of the pesticide treatments on soil bacterial communities. Our results revealed that, diuron degraded more slowly in sterilized soil than in unsterilized soil, which suggests that microbial biodegradation sped up the breakdown of diuron in tea field soil. In applying pesticides at a 10-fold field rate, the B+D treatment led to a slight decrease in the diuron degradation rate. In applying pesticides at a 50-fold field rate, the B+D and Tr+D treatments led to a significant decrease in the diuron degradation rate. During the experimental period, the diuron metabolite N'-[3,4-dichloro-phenyl]-N,N-methylurea (DCPMU) was detected in 10-fold field rate treatments; the DCPMU and N'-3,4-dichloro-phenylurea (DCPU) metabolites were detected in 50-fold field rate treatments. However, the quantity of these metabolites was less than the quantity of degraded diuron Thist indicates that diuron degradation may have produced other metabolites as well. Benomyl may inhibit the degradation of diuron and we observed less DCPMU in the B+D treatment compared to other treatments when applied at a 50-fold field rate. DGGE fingerprint and cluster analysis results indicate that D, Te+D and Tr+D 10-fold field rate treatments may increase the richness of bacterial communitiesat in tea fields, Tr+D and B+D impacted the bacterial communities at a 50-fold field rate. Impacts on bacterial communities may lead to eh inhibition of diuron degradation and thereby increase the persistence of diuron in the environment. Therefore, assessments are required when diuron is simultaneously applied with the fungicides benomyl and triadimefon in tea field soil.
Subjects
達有龍
降解
持久性
殺菌劑
土壤菌相
diuron
degradation
persistence
fungicide
soil bacterial community
Type
journal article